Synthetic Aperture Radar (SAR) is used for ground mapping as well as target identification. SAR imaging methods combine the amplitude and phase information of radar returns from a sequence of transmitted pulses. These transmitted pulses are from a relatively small antenna on a moving platform. As the platform moves, the information reflected from the sequence of pulses is combined to arrive at a high resolution SAR image.
The plurality of sequential returns creating a SAR image generated by the transmitted pulses along a presumed known path of the platform make up an array. Theoretically, during the array, amplitude as well as phase information returned from each of the pulses, for each of many range bins, is preserved. The SAR image is formed from the coherent combination of the amplitude and phase of return(s) within each range bin, motion compensated for spatial displacement of the moving platform during the acquisition of the returns for the duration of the array.
One difficulty presented in SAR imaging occurs when a number of radar pulse returns forming the required sequence of returns in an array may be missing. The missing pulses may arise because of, for example, multi-mode operation wherein a different mode is entered during an array. The missing pulses within the partial array blur the resulting SAR image, obfuscating details thus rendering it of limited utility, necessitating restoration of the missing pulse returns. A second difficulty may occur when portions of radar pulse returns are corrupted due to interference or obstruction of the radar line-of-sight. In either case, the SAR image will benefit through supplying substitute data that minimizes phase discontinuities and allows the existing signals to propagate. In the descriptions and claims herein, “corrupted data” refers to regions of either missing data or data actively corrupted due to interference or obstruction.